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Mauro Penasa's INV GC/REF GC group buy.

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awashi

awashi

Member
Joined 2005
built

Built the amp today =)
Really pleasant experience, thanks for labeling them resistors (well and most other parts as well :D) Brian! Saved a lot of time.
Everything was a perfect fit other than those 8 caps. Had a hard time with the Faston connectors, had to drill the holes on the PCB a bit wider to fit them in. Think I'll pry the female connectors open a bit too, they're really hard to plug in and remove.
The low ESR caps, the only way to identify them is by their color? Just went by that and count.
I so need to find a proper transformer soon. Won't let this beauty collect dust.

So thanks again Russ and Brian, you made my entry into the DIY realm a breeze :)
Pictures of my crummy work probably aren't necessary :rolleyes:

Edit: Typo
 
S

Seth Hensel

Member
Joined 2003
Finished the board in about 7 hours. The chassis it's going to live in is a couple of days away from completion, so I breadboarded a power supply and some temporary in/outs.

The short version: Sounds fantastic! Best the system has ever sounded. It truly is a "reference" amp.

Of course, the inevitable (for me) consequence of having something this good in the system is that it reveals the weaknesses elsewhere. The Foreplay II preamp that has served faithfully for over three years will have to go.

Thanks to Mauro, Russ, and Brian for making this project happen.
 
BrianDonegan

BrianDonegan

Member
Joined 2004
twistedpearaudio.com
So, I was just perusing the 3W replacements for R1, R4, R24 and R27 to see what's out there, and noticed this note in the datasheet for the Vishay/BC resistors (currently 1W).

http://www.vishay.com/docs/28729/pr010203.pdf

The resistors should be mounted 8mm above the board (+/-2mm). Mine are about 2-3 mm. They get warm to hot, but no problems so far. Just a tip for those who haven't soldered yet.

I think the 3W version would do well as a replacement, though they cost 4 times as much. The 2W verision is only twice as much.
 
Russ White

Russ White

Member
Joined 2005
twistedpearaudio.com
BrianDonegan said:
So, I was just perusing the 3W replacements for R1, R4, R24 and R27 to see what's out there, and noticed this note in the datasheet for the Vishay/BC resistors (currently 1W).

http://www.vishay.com/docs/28729/pr010203.pdf

The resistors should be mounted 8mm above the board (+/-2mm). Mine are about 2-3 mm. They get warm to hot, but no problems so far. Just a tip for those who haven't soldered yet.

I think the 3W version would do well as a replacement, though they cost 4 times as much. The 2W verision is only twice as much.
Click to expand...

Did you look at the IRC thick films? I can't remember how much I paid.
 
Russ White

Russ White

Member
Joined 2005
twistedpearaudio.com
mauropenasa said:
Any informations:

I have found any numerations not correct on the BOM and have corrected it ( only the serigraphy references, the quantities are correct ).I attach the corrected version to verify. I Creed that you did a good work, Brian.

LM3886 T now TF: The T version ( not iso ) has theoretically a better ability of dissipate of the heat ( internal ) toward the heatsink. In my LM3886 circuit it has to dissipate " theoretically " a lot of energy if the load is 4 ohms. This calculations however I am in " sinusoidal continues power" that doesn't exist in the ordinary music. I have done my test with the "T" type (not iso), but I believe that for an "moderate" use goes well the TF type ( iso ) for the reasons lists from Russ...

Heatsink: I Suggestion to use a type with 1-1.2 °C/W of Thermal Resistance, with vertical development ( like NS- AN1192 by BR100 mod. )

Ciao

Mauro
Click to expand...


So anything with less than 1.2 deg C/W thermal resistance should be OK.
 
T

Tergofante

Member
Joined 2006
Because i don't speak Englis, i wrote in Spanish:
Aqui añado mi contribución, pequeña.
He modificado la alimentación para disminuir el rizado y aumentar la Irms del los condensadores de filtro de alimentación, por trabajar a 100Hz.
Añado el esquema y la PCB
 

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